The present invention relates to a cathode ray tube device designed to reduce the alternating electric field emitted from the deflection yoke by providing a conductive film for electric field shielding on a funnel and a method for making the conductive film.
In recent years, there has been public concern for health hazards from electromagnetic waves. As for the, display monitor, the ill effect of the alternating electric field emitted mainly from the deflection yoke, that is, radial electric field extending from the deflection yoke, on human bodies is worried.
Countermeasures against the alternating electric field are disclosed in, for example, U.S. Pat. Nos. 5,357,166 and 5,304,891. In these publications, a conductive film for electric field shielding is formed on a glass bulb from a neck portion to a cone portion, and the deflection yoke is mounted on the conductive film via an insulation sheet interposed therebetween.
However, the insulating performance of the insulation sheet may deteriorate as time goes by.
Further, the insulation sheet narrows a gap between the cone portion and the deflection yoke and makes it difficult to insert a spoiler for convergence adjustment into the gap. The narrow gap also results in poor heat dissipation of the deflection yoke, raising the temperature in the deflection yoke and increasing the electric power loss.
Furthermore, the effect of the cost of the insulation sheet is not negligible.